Tools equipped with cutting inserts are commonly known as cutting tools used for cutting work of heat-resistant alloys. The “cutting insert” generally means a disposable cutting edge detachably attached to one end of the main body of a cutting tool, and is a tool component called a throw-away chip or a replaceable chip (see, for example, Patent Literature 1).
For the improved wear resistance, the cutting insert is generally made of a Sialon ceramic material (Sialon sintered body) or an alumina ceramic material reinforced with SiC whiskers (SiC whisker-reinforced alumina material). As is known in the art, the wear resistance includes resistance against notch wear and resistance against VB wear. The “resistance against notch wear” means a characteristic relating to physical wear-induced deterioration. The “resistance against VB wear” means a characteristic relating to chemical wear-induced deterioration (“flank wear”).
The cutting insert made of the Sialon sintered body generally tends to have the better resistance against notch wear but the worse resistance against VB wear of the wear resistance, compared with the cutting insert made of SiC whisker-reinforced alumina material. For the better wear resistance of the cutting insert made of the Sialon sintered body, it is required to improve the resistance against VB wear of the Sialon sintered body, while preventing deterioration of the resistance against notch wear of the Sialon sintered body. This requirement is not restricted to the cutting insert but is commonly found for various working tools made of the Sialon sintered body.